[U-Boot] DWMMC crontroller in Exynos4412

Humberto López León
2015-08-26T17:24:26Z

Hi Przemyslaw,

On 08/26/2015 10:12 AM, Przemyslaw Marczak wrote:
> Hi Humberto,
>
> On 08/26/2015 03:40 PM, Humberto L?pez Le?n wrote:
>> Hi community,
>>
>> thank you all for answering my questions.
>>
>> On 08/26/2015 02:53 AM, Przemyslaw Marczak wrote:
>>> Hi,
>>>
>>> On 08/26/2015 08:23 AM, Jaehoon Chung wrote:
>>>> On 08/26/2015 11:26 AM, Simon Glass wrote:
>>>>> +Samsung people
>>>>>
>>>>> Hi,
>>>>>
>>>>> On 25 August 2015 at 13:10, Humberto L?pez Le?n <humberto@uclv.cu>
>>>>> wrote:
>>>>>> Hi Simon,
>>>>>> I'm working on implementing a driver for SD/MMC cards in the
>>>>>> framework
>>>>>> GenodeOS. I think you could help me with your experience in this
>>>>>> type of
>>>>>> implementation in the u-boot.
>>>>>> The hardware platform on which the driver will work is a ODROID-x2
>>>>>> (exynos4412). I use the DWMMC contoller, but I'm not sure if this
>>>>>> is the
>>>>>> right controller to handle SD/MMC cards in Exynos4412 SoC. The SDHCI
>>>>>> controller is most appropriate?
>>>>
>>>> If you're using exynos4412 board, you can choose sdhci or dwmmc
>>>> controller for eMMC, not SD/SDIO.
>>>> And in my experiment, dwmmc controller is more appropriate than
>>>> sdhci.(ex, performance)
>>>>
>>>
>>> It depends which mmc channel is used. In Exynos4412, there are 5
>>> channels, but some channel configurations shares GPIO pins:
>>> - MMC0 - sdhci
>>> - MMC1 - sdhci, or MMC0 8-bit
>>> - MMC2 - sdhci - Odroid SD card, 4-bit mode
>>> - MMC3 - sdhci - or MMC2 8-bit
>>> - MMC4 - dwmmc, uses MMC0 pins for 4-bit, and MMC0-1 for 8-bit mode
>>>
>>> Odroid is using MMC2(sdhci) and MMC0/4(sdhci or dwmmc).
>>>
>>> So for eMMC cards you can use the dwmmc, and as Jaehoon wrote it is
>>> recommended for the better performance, but for SD card you must use
>>> sdhci controller.
>> This information is valuable to me, but now I would help if you tell me
>> where I can find the code of SDHCI controller for the SD card of
>> Exynos4412 in U-boat 2015.04-rc2 for a implementationtation reference. I
>> was reviewing the file exynos_dw_mmc.c as reference of DWMMC driver,
>> but now I have no idea what the file where the SDHCI driver for the
>> exynos4412 is implemented.
>>
>> Thank you very much for your collaboration.
>>
>>
>>
>
> Please check those files:
> - drivers/mmc/s5p_sdhci.c
> - drivers/mmc/sdhci.c
>
> But, isn't the kernel a better reference for you?
Thanks for your time to answer my questions. I have reviewed the
implementation of SDHCI controller in the Linux kernel for Odroid
(https://github.com/hardkernel/linux/blob/odroid-3.0.y/), but have not
been able to identify the specific implementation that is used for
handling of SD cards in exynos4412.
You know in what file this controller is implemented? I think the file
should be drivers/mmc/host/sdhci-s3c.c
(https://github.com/hardkernel/linux/blob/odroid-3.0.y/drivers/mmc/host/sdhci-s3c.c)
but I'm not sure.
What do you think?

Thanks again.

Humberto